Dokimo Verify API (GET) - scheme demo: recomputes a sample dokimo-merkle-v1 proof to its root. For real caller verificat

Dokimo Verify API (GET) - scheme demo: recomputes a sample dokimo-merkle-v1 proof to its root. For real caller verification, POST /paid/verify (recompute + on-chain anchor check). Scheme: /merkle-spec.html.